Under the action of an external electric field, an electrochromic material undergoes an oxidation-reduction reaction and at the same time causes a reversible change in light transmission or reflection, which appears as a reversible coloring phenomenon. Electrochromic materials can be divided into inorganic electrochromic materials and organic electrochromic materials. Inorganic electrochromic materials have advantages such as high cycling stability, strong adhesion and high thermal stability, as well as long service-life, etc.; organic electrochromic materials have advantages such as fast response, rich color-changes, good processability, ease of designing molecules, and low costs. A single inorganic or organic electrochromic material has its disadvantages, and therefore organic-inorganic composite electrochromic materials have been gaining more and more attention.
At present, it is also a focus of research to produce an electrochromic material with better performances, by choosing appropriate types of organic and inorganic materials and utilizing synergy effects between the structures and performances of these materials. Conventional organic-inorganic composite electrochromic thin films have the problems as follows. As an electrochromic device is increased in size, for example, when such device is applied in a floor-to-ceiling window, a car-window, or other large-sized applications, the uniformity of the display will become much degraded, that is, there are substantial difference in transmittance among various regions (such as upper, lower, left, right, center portions) of the display device during color-displaying, and this greatly influences the display effect of the electrochromic device.